Vivarium top cover

FIG. 1 is an isometric view of a vivarium top cover showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevation view thereof;

FIG. 4 is a right side elevation view thereof;

FIG. 5 is a rear elevation view thereof;

FIG. 6 is a left side election view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines are for illustration only and form no part of the claimed design.